Oscar Winner Hildur Guðnadóttir Confirms She Is Scoring 'The Bell Jar' with Billie Eilish

Oscar-winning "Joker" composer Hildur Guðnadóttir has confirmed she is scoring Sarah Polley's "The Bell Jar," the Sylvia Plath adaptation that gives Billie Eilish her first starring role. The film has already wrapped production.

Guðnadóttir broke the news in an interview with Variety at this year's World Soundtrack Awards in Ghent, where she was guest of honor. She described the project as "one of the most exciting projects I've ever done" and called Plath's 1963 novel "one of the most amazing books ever written."

How does a pop star change the scoring process?

Quite a bit, according to the composer. Eilish, who has won her own Oscars for songwriting, comes to set already fluent in how music gets made.

"You know she understands the process that goes into writing music, so what you write can really resonate with her," Guðnadóttir told Variety.

That's unusual. Most film actors don't write music, so a composer's themes can feel abstract to them. Here, Guðnadóttir could talk shop with her lead before cameras rolled.

"We talked about what we envisioned for the music, and how we could translate what Sylvia experiences into it," she said. "For me, the core of Plath's writing is that she's searching for identity. She keeps asking, 'Who am I?' and then uses her writing to understand that. Billie, Sarah and I have been exploring how we hear that, how to translate it into music, and what music Sylvia herself might have been listening to."

The partnership with Polley builds on their work together. The two first collaborated on 2022's Oscar-winning "Women Talking," and on "The Bell Jar" Guðnadóttir joined early, writing themes the filmmaker could play on set during shooting.

Guðnadóttir also offered a reading of Plath that pushes against the writer's usual framing.

"People tend to remember the drama of her story, that she had mental health struggles and a sad end," she said. "But her writing is so full of life, creativity and energy, and that's what people tend to forget. I really hope this film can bring that back to center and celebrate her magnificent way of living."

What else is she working on?

Hours before flying to Belgium, Guðnadóttir was still mixing "Enemies," the A24 thriller produced by Ari Aster. Directed by Henry Dunham and starring Jeremy Allen White and Austin Butler, the Chicago-shot cop drama let her work with urban ambient sound.

"I'm working a lot with environmental textures and city sounds, and how they can relate to the film's music," she said. "Listening is always at the heart, along with my curiosity."

She also revisited "28 Years Later: The Bone Temple," Nia DaCosta's installment in the franchise, and revealed the score's most unusual instrument. Director DaCosta wanted strings; Guðnadóttir balanced their ethereal quality with percussion made from actual bones — sourced through a friend's hamburger restaurant outside Berlin.

"I have a friend who runs a hamburger place just outside of Berlin," she explained. "She has a good relationship with her butcher, so I got a deal to take the leftover bones. All the percussion in the film is made from bones. The shoulder bones made interesting clapping percussion, and the bigger ones suited deeper beating percussion. The smaller ones were better suited to flutes."

And yes, she prepared the instruments herself: "I do everything myself, and that includes boiling the bones. I'm very hands-on."

Guðnadóttir said she would return to the "28 Years Later" franchise whenever the next installment arrives. For now, "The Bell Jar" — a film about a writer asking who she is, scored by three Oscar winners asking the same question in music — awaits its release date.